Micromachining and mechanical properties of GaInAs/InP microcantilevers

Micro cantilever beams have been fabricated by selective wet etching of GaInAs/InP heterostructures with InP layer used as a sacrificial layer and GaInAs regions acting as semiconductor masks and/or etch stop layers. With deep front side micromachining, microstructures of one micron thick were fabricated and subsequently characterized by means of a nanoindentation system. For GaInAs microstructures, a Young’s modulus between 70 and 100 GPa range depending on analysis assumptions was calculated. For tri-layered structures with one micron thick sacrificial layer, we faced the problem of stiction. For addressing this issue, we fabricated several series of beam sets which differ mainly in length and width. A critical length corresponding to the transition between pinned and self-sustaining structures was found and subsequently analysed in terms of Young’s modulus with values consistent with mechanical measurements.